A wireless apparatus built in a cellular phone or the like includes a wireless unit (also called a “radio frequency (RF) unit”) and a baseband processing apparatus. The interface between the wireless unit and the baseband processing apparatus is configured with lines including an analog signal line and a digital or analog control line.
In recent years, an RFIC (RF Integrated Circuit) included in a wireless unit can be made from a CMOS (Complementary Metal-Oxide Semiconductor) circuit. The RFIC can include an analog-digital converter (ADC) and a digital-analog converter (DAC).
Following this, an interface has been standardized for digital signal connection between an RFIC and a digital IC for baseband processing. The interface standardized for digital signal connection between an RFIC and a digital IC includes “DigRF”.
Version 3 of the DigRF standard (DigRF v3) is for an LVDS transmission frequency of about 300 MHz, and a DigRF packet does not include an error determination bit. Therefore, according to Version 3 of the DigRF standard, if an error occurs in a DigRF packet, retransmission control is not executed.
In contrast to DigRF v3, Version 4 of the DigRF standard (DigRF v4) is for an LVDS transmission frequency of about 1 GHz, and an error determination bit is provided in a DigRF packet. Therefore, in DigRF v4, error detection is executed for data between an RFIC and a baseband processing apparatus, and if an error is detected, retransmission control is executed for the data (see, for example, Patent Document 1). For example, when data is transmitted from an RFIC to a baseband processing apparatus, the baseband processing apparatus executes error detection in the data from the RFIC. If detecting an error in the data from the RFIC, the baseband processing apparatus makes a retransmission-request of the data to the RFIC. In response to receiving the retransmission-request of the data, the RFIC transmits the data again to the baseband processing apparatus.